Not sure if this will help, but with my USB-C monitor the default brightness/contrast is poor, and requires manually fiddling with the settings on every boot/resume from sleep, so I found a Linux utility that does the fiddling for me:

    cat ~/bin/brightness 
    #!/bin/bash
    #
    echo "increasing brightness/contrast of external monitor"
    /usr/local/bin/ddcutil --display 1 setvcp 10 40
    /usr/local/bin/ddcutil --display 1 setvcp 12 10

Tie the above in with your init/resume scripts and you're good to go (assumes that your issue isn't limited by the hardware itself).

I'll give that a try later, although I think mine is hardware limited. It's probably because it's a cheap knockoff one tho, but it works for terminal use, or anything that has a high contrast.